Application value of double-layer spectral detector CT in differentiating central lung cancer from atelectasis.

BACKGROUND: Central lung cancer with obstructive atelectasis is very common in clinical practice. Determination of the tumor borderline is important. Conventional computed tomography (CT) alone may not be sufficiently accurate to distinguish central lung cancer from obstructive atelectasis. Spectral CT can improve the soft-tissue resolution greatly. In this study, we evaluated the application value of double-layer spectral detector CT in differentiating central lung cancer from atelectasis. METHODS: A total of 51 patients (37 males) with pathologically confirmed central lung cancer accompanied by atelectasis were enrolled. The rates of differentiation between tumors and atelectasis were retrospectively analyzed using conventional CT and three types of spectral images (40 keV virtual monoenergetic imaging, iodine density map, and their fusion image) of unenhanced scans as well as arterial and venous phases. Cochran's Q test and Friedman test were used to compare the differentiation rates and the maximal diameters of the tumors in each image. RESULTS: Among the 51 cases, conventional CT, 40 keV monoenergetic, iodine density, and their fusion images of the venous phase were successful in differentiating tumors from atelectasis in 17 (33.33%), 35 (68.63%), 39 (76.47%), and 38 (74.51%) cases, respectively. The differentiation rates of the 40 keV monoenergetic, iodine density, and fusion images were significantly higher than those of conventional images (χ2=-0.35, -0.43, and -0.41, respectively, all P<0.001). There were no significant differences in the differentiation rates among the 40 keV monoenergetic, iodine density, and fusion images (χ2=-0.06, -0.08, 0.02, respectively, all P=1.00). The maximal tumor diameters in the four images did not significantly differ (χ2=3.61, P=0.31). Conventional and spectral images of unenhanced and arterial phases could not/barely identify the tumor borderlines. CONCLUSIONS: Venous-phase spectral images of double-layer spectral detector CT can differentiate most central lung cancers from atelectasis, and the maximal diameter measurement of the tumor is reliable. Double-layer spectral detector CT can accurately identify the borderlines of most central lung cancers through spectral images during routine CT examinations without requiring other imaging modalities. Therefore, this method has considerable clinical value for applications in tumor staging, efficacy evaluation, and radiotherapy.

Differential diagnosis of pulmonary nodular mucinous adenocarcinoma and tuberculoma with dynamic CT: a retrospective study.

Background: Pulmonary nodular mucinous adenocarcinoma (PNMA) tends to be easily misdiagnosed as tuberculoma in practice. In this study, we aimed to discriminate PNMA from tuberculoma with dynamic computed tomography (CT). Methods: In this study, 38 consecutive pathologically confirmed cases of PNMA and 23 cases of tuberculoma from January 2015 to December 2019 were retrospectively collected. The mean CT attenuations of each lesion were examined. The values on the plain scan, the venous scan, and the enhanced values (CT attenuation of lesion of venous scan minus that of the plain scan) were tested with an independent t-test pair-wisely. Receiver operating characteristic (ROC) curve analyses were performed to test the differential diagnosis values. The presence of satellite lesions was determined with the chi-square test. Results: The mean CT attenuation of tuberculoma shown on the plain scan was significantly higher than that of PNMA (35.15±16.00 vs. 24.00±12.67 HU; P<0.01). The enhanced value of tuberculoma on venous scan was significantly lower than that of PNMA (13.44±13.40 vs. 22.52±14.00 HU; P=0.02). The optimum CT attenuation of the plain scan and the enhanced value for differential diagnosis were 28.80 and 14.25 HU [area under the curve (AUC) =0.72, 95% confidence interval (CI): 0.58-0.86; and AUC =0.70, 95% CI: 0.59-0.84], with sensitivity (78.3% vs. 71.1%) and specificity (63.8% vs. 69.6%) respectively. The satellite lesions were more often observed in the tuberculoma group (P<0.01). Conclusions: The CT attenuation of the plain scan, the enhanced value after enhancement, and the presence of satellite lesions might be useful in differentiating PNMA from tuberculoma.

Early Changes in Apparent Diffusion Coefficient for Salivary Glands during Radiotherapy for Nasopharyngeal Carcinoma Associated with Xerostomia.

Objective: To evaluate the early changes in the apparent diffusion coefficient (ADC) of the salivary glands during radiotherapy (RT) and their association with the degree of xerostomia at 6 months after RT in patients with nasopharyngeal carcinoma (NPC). Materials and Methods: We enrolled 26 patients with NPC who underwent RT. Each patient underwent diffusion-weighted MRI of the salivary glands at rest and with gustatory stimulation within 1 week before RT and 2 weeks after the beginning of RT. The ADC at rest (ADCR) and increase and increase rate with stimulation (ADCI, ADCIR) of the submandibular and parotid glands were calculated. The differences in the variables' values between 2 weeks after the beginning of RT and baseline (ΔADCR, ΔADCI, and ΔADCIR) were compared to the degree of xerostomia at 6 months after RT. Results: The ADCR of the submandibular and parotid glands were both significantly higher at 2 weeks after the beginning of RT than found at baseline (both p < 0.01). The ADCI and ADCIR for the parotid glands were both significantly lower at 2 weeks after the beginning of RT than found at baseline (both p < 0.01). ΔADCI and ΔADCIR of the parotid glands were associated with the degree of xerostomia at 6 months after RT (r = -0.61 and -0.72, both p < 0.01). Conclusion: The ADCs of the salivary glands change early during RT. The differences in the ADC increase and increase rate of the parotid glands between 2 weeks after the beginning of RT and baseline were associated with the degree of xerostomia at 6 months after RT.

Analysis of computed tomography and pathological observations of non-Hodgkin lymphomas with peritoneal, omental and mesenteric involvement.

The aim of the present study was to evaluate the association between computed tomography (CT) images and the pathological observations of non-Hodgkin lymphoma (NHL) patients with peritoneal, omental and mesenteric involvement. In total, 26 patients suffering from an NHL with peritoneal, omental or mesenteric involvement were reviewed retrospectively, and the observed CT scan characteristics were analyzed. In addition, associations among the CT scan characteristics and the NHL subtypes, including diffuse large B-cell, mantle cell, follicular cell and T-cell lymphoma, were evaluated. The CT scan characteristics of the NHLs with peritoneal, omental and mesenteric involvement included peritoneal cord-like thickening, peritoneal omental nodular and swelling thickening, omental cake-like thickening and mesenteric mass. The probability of peritoneal linear, omental nodular and swelling thickening was found to be higher in diffuse large B-cell lymphoma cases compared with cases of other NHL subtypes (P<0.05). However, the probability of omental cake-like thickening and mesenteric mass was not found to be significantly different among the NHL subtypes (P>0.05). Signs of peritoneal, omental and mesenteric involvement were observed in the CT scans of all the NHL subtypes, particularly in diffuse large B-cell lymphoma cases. Therefore, linear, omental nodular and swelling thickening were characteristic of diffuse large B-cell lymphoma, while omental cake-like thickening and mesenteric mass were observed in all NHL subtypes.